94 s-10 blazer 4.3w no power under load

Did maintenance tune up, plugs, wires, cap,rotor. Left shop came back 3 days later on the hook. changed distributor. Now has no power in drive. veaple@cox .net

More Info on the vehicle, it was hard to start when cold checked fuel press, does have a drop when shut off engine. But I don't think that the lack of power would come from this. because it had good pick up before I did tune up that included fuel filter. also no check engine light was or has come on. No codes have come on. Gas milage has dropped dramatically. Im really at a loss right at this time. I just can't throw a bunch of money at this thing. Has 293000 miles

Was the ign timing set right?
I would start with checking timing.
MT

yes timing is set correctly, changed distributor because timing was jumping some. That seemed to make a difference but still have some lack of power. I suggested the fuel pump change for hard to start cold, or sitting for and hour or so. Looks like this problem will be on hold for awhile Lack of funds for now.

Was it set with the est jumper wire disconnected?

What is the engine vacuum reading at idle and at 2 K rpm

Fuel pressure and fuel pump can be tested with a fuel pressure gauge.